1920s plate advertising Yeungling Ice Cream. The company was founded in the 1920 and still exists today - their URL linked.
Curiously, members of the same family founded the Yeungling Brewery in 1829 in Pennsylvania, USA, which wikipedia says is the oldest still operating brewery in the United States. (I can hear the snickers clear across the pond about calling that an old brewery!) During prohibition, the family started a dairy and ice cream company, which shut down in 1985, but was started up again in 2014. This is a 1920s vintage plate hawking their ice cream.
A machine was patented in 1926 that produced something similar to soft serve but soft serve didn’t become commercially available until the 1930s.